When David Driskill, his son and three buddies decided to canoe and kayak down the Trinity River on August 7, they were prepared for any challenge the river might throw at them. What they weren't ready for was a dangerous surprise thrown at them by the city's construction of an artificial stretch of whitewater.

Between Sylvan Avenue and Loop 12, the river is surrounded by a wide flood plain until it reaches the Santa Fe Railroad trestle, where the city is creating a $4 million-plus dollar whitewater park -- the so-called Standing Wave -- for recreational kayakers. To accommodate construction, the river's main channel is blocked by two coffer dams while workers drain the water in between them. The river funnels through a narrow diversion channel cut through the east embankment, in effect forming a small island.

"We might have been able to avoid it, but we just didn't see it coming." Driskill says. The diversion channel is less than half the size of the main waterway and, at its mouth, drops about five feet back into the main channel. Making navigation dicier, a large column supporting a temporary bridge splits the channel. The current forced Driskill's group to the left side of the column, shooting their boats onto a rocky embankment. All but one kayak capsized.

Driskill's son Mike found himself caught by thick, black fabric laid down on the channel's banks to prevent erosion. His first thought, he says, was, "I can't let go, I need to get over." But the current was too strong. He says he finally slipped under the material and was washed out with every one else, who all carry a few painful reminders of the trip. "I thought I was going to die," Mike Driskill says.

"It's basically a death trap," says Charles Allen, who runs Trinity River Expeditions and rented the boats and equipment to the group. "If you're not proficient, if you haven't been on the water for a while, I wouldn't send you down this."

Allen, angry that he was not alerted to the danger and that no warnings were posted along the river, attempted to contact city officials with little success. He wants to know why the city, in its efforts to raise interest in the Trinity, is scaring away those who already paddle down the river for recreation. Allen's company sees hundreds of recreational boaters down the river every year, many down the part of the river in question. "This is the entrance to the Great Trinity Forest," Allen says, "and the river is the only real way to see it."

The U.S. Army Corps of Engineers, which has already inspected the diversion channel, refused to comment on whether the river is navigable at the location, directing Unfair Park instead to the city. John Reynolds, project manager for the Standing Wave, confirmed that the river is not safe for travel at that construction area and said he has decided that "the best course at this time is to close off access to the channel." He no doubt has his hands full with a development whose price tag has jumped from an estimate of $445,000 to $3 million to $4 million.

Reynolds cannot predict when the construction will end. The work permit calls for completion by next March, but the pace of construction depends largely on the weather.

That could make it tough on Allen's business. Standing next to the channel last week, he gestured toward the river. "October is one of the wettest months in Dallas," he said, "and all this will probably be underwater at some point."

Allen had already canceled a few canoe trips last week for safety reasons. "I don't want to get in a battle over this," he said, "but I don't want to see anybody hurt either."